Method and apparatus for minimizing unwanted dynamics in a physical system

• US 5,638,267 A
• Filed: 06/15/1994
• Issued: 06/10/1997
• Est. Priority Date: 06/15/1994
• Status: Expired due to Term

• Current Assignee: Convolve Incorporated
• Original Assignee: Convolve Incorporated
• Inventors: Pasch, Kenneth, Singhose, William E., Rappole, Bert W. Jr., Derezinski, Stephen J. III, Singer, Neil C.
• Primary Examiner(s): RUGGIERO, JOSEPH F
• Application Number:
  US08/259,880
• Time in Patent Office: 1,091 Days
• Field of Search: 364/148, 364/152, 364/153, 364/176, 364/177, 364/164, 364/165, 364/183, 364/149-151, 364/157, 364/572, 364/574, 364/724.01, 364/724.12, 364/728.01 , 364/728.02, 364/553, 364/561, 364/724.19, 318/561
• US Class Current: 700/28
• CPC Class Codes: B25J 9/1635 flexible-arm control
• CPC Class Codes: G05B 2219/41217 Command preshape, guidance, reference for better dynamic response, forcing feedforward
• CPC Class Codes: G05B 5/01 electric

Abstract

Method and apparatus for minimizing unwanted dynamics in a physical system response. Constraints on the input and on the unwanted dynamics are established, and an impulse sequence which satisfies the constraints is determined. The impulse sequence is convolved with an arbitrary command input to produce a shaped input which is used to drive physical system, thereby minimizing unwanted dynamics. The constraints on the input and on the unwanted dynamics may be selected to achieve shaped inputs and residual unwanted dynamics of various characteristics.

Claims

1. A method for controlling a physical system by generating an input to the system to minimize unwanted dynamics in the system response comprising;

establishing expressions quantifying the unwanted dynamics;

establishing first constraints bounding an available input to the dynamic system;

establishing second constraints bounding the unwanted dynamics;

finding a solution which allows maximum variations in physical system characteristics and is used to generate the input while still satisfying the first and second constraints; and

controlling the physical system based on the input to the physical system whereby unwanted dynamics are minimized.

2. The method of claim 1 wherein the solution is a sequence of impulses which satisfies the first and second constraints while allowing maximum variations in physical system characteristics.

3. The method of claim 1 wherein the solution is a sequence of pulses of finite duration which satisfies the first and second constraints while allowing maximum variations in physical system characteristics.

4. The method of claim 1 wherein the solution is a sequence of impulses or pulses that begin at specified time intervals.

5. The method of claim 1 wherein the solution is a sequence of impulses or pulses which have specified amplitudes.

6. The method of claim 1 wherein the solution is a sequence of pulses which are fixed in amplitude but variable in duration.

7. The method of claim 1 wherein the solution is a sequence of impulses or pulses which are variable in amplitude but fixed in duration.

8. The method of claim 1 wherein the physical system is an electrical system.

9. The method of claim 1 wherein the physical system is a mechanical system.

10. The method of claim 1 wherein the physical system is a chemical system.

11. The method of claim 1 wherein the dynamic system has a single vibrational mode characterized by an undamped natural frequency ω

and non-zero damping ratio ζ

; and

the second constraint comprises bounding residual vibrations in the physical system.

12. The method of claim 11 wherein

the solution is a sequence of n impulses of amplitude A_i and location t_i, for i=1 . . . n, with t₁ =0;

the expression quantifying the unwanted dynamics is

space="preserve" listing-type="equation">R(Ω

)=exp(-ζ

Ω

t.sub.N){[Σ

A.sub.i exp (ζ

Ω

.sub.i) cos(mΩ

t.sub.i)].sup.2 +[Σ

A.sub.i exp (ζ

Ω

.sub.i) sin (mΩ

t.sub.i)].sup.2 }.sup.1/2

where m=(1-ζ

²)^1/2, R(Ω

) is the ratio of the residual vibration produced by the sequence of impulses to the residual vibration produced by a single impulse of amplitude Σ

A_i, if the physical system had an undamped natural frequency Ω

, and the summation is over i=1 . . . n; and

the second constraint further comprises selecting a maximum V bounding the residual vibration R(Ω

).

13. The method of claim 12 wherein the impulses are based on a first set of equations ##EQU52##

14. The method of claim 13 wherein the sequence of impulses is based on an approximate solution to the first set of equations.

15. The method of claim 14 wherein the number of impulses is three and the approximate solution is

16. The method of claim 14 wherein the number of impulses is four, V=0.05 and the approximate solution is

17. The method of claim 1 wherein

the dynamic system has a single vibrational mode characterized by an undamped natural frequency ω

and a damping ratio ζ

=0;

the solution is a sequence of four impulses of amplitude A_i and location t_i ;

the expression quantifying the unwanted dynamics is

space="preserve" listing-type="equation">R(Ω

)={[Σ

A.sub.i cos (Ω

t.sub.i)].sup.2 +[Σ

A.sub.i sin (Ω

t.sub.i)].sup.2 }.sup.1/2

where R(Ω

) is the ratio of the residual vibration produced by the sequence of impulses to the residual vibration produced by a single impulse of amplitude Σ

A_i, if the physical system had a natural frequency Ω

;

the second constraint comprises selecting a maximum V bounding the residual vibration R(Ω

); and

the four impulses are defined by the equations

space="preserve" listing-type="equation">A.sub.1 =(3×

.sup.2 +2×

+3V.sup.2)/(16×

)

space="preserve" listing-type="equation">A.sub.2 =0.5-(3×

.sup.2 +2×

+3V.sup.2)/(16×

)

space="preserve" listing-type="equation">A.sub.3 =0.5-(3×

.sup.2 +2×

+3V.sup.2)/(16×

)

space="preserve" listing-type="equation">A.sub.4 =(3×

.sup.2 +2×

+3V.sup.2)/(16×

)

space="preserve" listing-type="equation">t.sub.1 =0

space="preserve" listing-type="equation">t.sub.2 =0.5T.sub.d

space="preserve" listing-type="equation">t.sub.3 =T.sub.d

space="preserve" listing-type="equation">t.sub.4 =1.5T.sub.d

where ##EQU56## and T_d =2π

/ω

18. The method of claim 1 wherein the dynamic system has p vibrational modes characterized by undamped natural frequencies ω

_i and damping ratios ζ

_i, i=1 . . . p, establishing p sets of constraint equations with the equations representing the first and second series of constraints, and finding a solution which allows maximum variations in physical system characteristics while still satisfying the p sets of constraints.

19. A method for controlling a physical system by generating an input to the system to minimize unwanted dynamics in the system response comprising;

establishing expressions quantifying the unwanted dynamics;

establishing first constraints bounding an available input to the dynamic system;

establishing second constraints bounding the unwanted dynamics;

finding a minimum length solution which is used to generate the input while satisfying the first and second constraints; and

controlling the physical system based on the input to the physical system whereby unwanted dynamics are minimized.

20. The method of claim 19 wherein the solution is a minimum length sequence of impulses which satisfies the first and second constraints.

21. The method of claim 19 wherein the solution is a minimum length sequence of pulses of finite duration which satisfies the first and second constraints.

22. The method of claim 19 wherein the solution is a sequence of impulses or pulses that begin at specified time intervals.

23. The method of claim 19 wherein the solution is a sequence of impulses or pulses which have specified amplitudes.

24. The method of claim 19 wherein the solution is a sequence of pulses which are fixed in amplitude but variable in duration.

25. The method of claim 19 wherein the solution is a sequence of impulses or pulses which are variable in amplitude but fixed in duration.

26. The method of claim 19 wherein the physical system is an electrical system.

27. The method of claim 19 wherein the physical system is a mechanical system.

28. The method of claim 19 wherein the physical system is an chemical system.

29. The method of claim 19 wherein the dynamic system is characterized by an undamped natural frequency ω

and damping ratio ζ

, and the second constraint comprises bounding residual vibrations in the physical system.

30. The method of claim 29 wherein

the solution is a sequence of an odd number n impulses of amplitude A_i and location t_i, for i=1 . . . n, with t₁ =0;

the expression quantifying the unwanted dynamics is

space="preserve" listing-type="equation">R(Ω

)=exp (-ζ

Ω

t.sub.N){[Σ

A.sub.i exp (ζ

Ω

t.sub.i) cos (mΩ

t.sub.i)].sup.2 +[Σ

A.sub.i exp (ζ

Ω

t.sub.i) sin (mΩ

t.sub.i)].sup.2 }.sup.1/2

where m=(1-ζ

²)^1/2, R(Ω

) is the ratio of the residual vibration produced by the sequence of impulses to the residual vibration produced by a single impulse of amplitude Σ

A_i, if the physical system had an undamped natural frequency Ω

, and the summation is over i=1 . . . n;

the second constraint further comprises selecting a maximum V bounding the residual vibration R(Ω

); and

the impulse sequence is based on a first set of equations

space="preserve" listing-type="equation">A.sub.i =P

space="preserve" listing-type="equation">A.sub.i =2P(-1).sup.i-1 for i=2 . . . n-1

space="preserve" listing-type="equation">A.sub.n =P+1

where P is a pre-selected peak partial sum bounding the input; and

on a second set of equations

space="preserve" listing-type="equation">R(ω

)=0

space="preserve" listing-type="equation">R(ω

.sub.lo,k)=V and R(ω

.sub.hi,k)=V for odd k

space="preserve" listing-type="equation">R(ω

.sub.lo,k)=0 and R(ω

.sub.hi,k)=0 for even k

space="preserve" listing-type="equation">dR(ω

.sub.lo,k)/dΩ

=0 and dR(ω

.sub.hi,k)/dΩ

=0 for odd k

where k=1 . . . Q, Q is the number of humps in R(Ω

), and ω

_lo,Q <

ω

_lo,Q-1 <

. . . <

ω

_lo,1 <

ω

<

ω

_hi,1 <

. . . <

ω

_hi,Q-1 <

ω

_hi,Q, for even Q;

or a second set of equations

space="preserve" listing-type="equation">R(ω

)=V

space="preserve" listing-type="equation">dR(ω

)/dΩ

=0

space="preserve" listing-type="equation">R(ω

.sub.lo,k)=0 and R(ω

.sub.hi,k)=0 for odd k

space="preserve" listing-type="equation">R(ω

.sub.lo,k)=V and R(ω

.sub.hi,k)=V for even k

space="preserve" listing-type="equation">dR(ω

.sub.lo,k)/dΩ

=0 and dR(ω

.sub.hi,k)/dΩ

=0 for even k

where k=1 . . . Q, Q is the number of humps in R(Ω

), and ω

_lo,Q <

ω

_lo,Q-1 <

. . . <

ω

_lo,1 <

ω

<

ω

_hi,1 <

. . . <

ω

_hi,Q-1 <

ω

_hi,Q, for odd Q.

31. The method of claim 30 wherein the locations t_i of the impulses are based on an approximate solution to the second set of equations.

32. The method of claim 31 wherein V=0.05, P=1 and the approximate solution is:

space="preserve" listing-type="equation">t.sub.i =0

space="preserve" listing-type="equation">t.sub.2 =(0.15687+0.24004ζ

+0.20367ζ

.sup.2)T.sub.d

space="preserve" listing-type="equation">t.sub.3 =(0.28151+0.10650ζ

+0.09280ζ

.sup.2)T.sub.d

space="preserve" listing-type="equation">t.sub.4 =(0.63431+0.33886ζ

-0.12776ζ

.sup.2)T.sub.d

space="preserve" listing-type="equation">t.sub.5 =(0.68414+0.18236ζ

+0.00839ζ

.sup.2)T.sub.d

where ##EQU57##

33. The method of claim 31 wherein V=0.05, P=2 and the approximate solution is:

space="preserve" listing-type="equation">t.sub.1 =0

space="preserve" listing-type="equation">t.sub.2 =(0.11955+0.16127ζ

+0.05206ζ

.sup.2)T.sub.d

space="preserve" listing-type="equation">t.sub.3 =(0.26356+0.12551ζ

-0.03963ζ

.sup.2)T.sub.d

space="preserve" listing-type="equation">T.sub.4 =(0.49804+0.15508ζ

-0.24101ζ

.sup.2)T.sub.d

space="preserve" listing-type="equation">t.sub.5 =(0.56866+0.04558ζ

-0.18732ζ

.sup.2)T.sub.d

where ##EQU58##

34. The method of claim 31 wherein V=0.05, P=3 and the approximate solution is:

space="preserve" listing-type="equation">t.sub.1 =0

space="preserve" listing-type="equation">t.sub.2 =(0.10219+0.12192ζ

+0.01197ζ

.sup.2)T.sub.d

space="preserve" listing-type="equation">t.sub.3 =(0.24639+0.11404ζ

-0.07655ζ

.sup.2)T.sub.d

space="preserve" listing-type="equation">t.sub.4 =(0.44526+0.11468ζ

-0.22230ζ

.sup.2)T.sub.d

space="preserve" listing-type="equation">t.sub.5 =(0.51719+0.02439ζ

-0.19225ζ

.sup.2)T.sub.d

where ##EQU59##

35. The method of claim 31 wherein V=0.10, P=1 and the approximate solution is:

space="preserve" listing-type="equation">t.sub.1 =0

space="preserve" listing-type="equation">t.sub.2 =(0.16136+0.24772ζ

+0.31367ζ

.sup.2)T.sub.d

space="preserve" listing-type="equation">t.sub.3 =(0.28547+0.11044ζ

+0.19967ζ

.sup.2)T.sub.d

space="preserve" listing-type="equation">t.sub.4 =(0.63719+0.33687ζ

-0.14612ζ

.sup.2)T.sub.d

space="preserve" listing-type="equation">t.sub.5 =(0.68919+0.17941ζ

-0.01215ζ

.sup.2)T.sub.d

where ##EQU60##

36. The method of claim 31 wherein V=0.10, P=2 and the approximate solution is:

space="preserve" listing-type="equation">t.sub.1 =0

space="preserve" listing-type="equation">t.sub.2 =(0.12207+0.16808ζ

+0.07038ζ

.sup.2)T.sub.d

space="preserve" listing-type="equation">t.sub.3 =(0.26661+0.13190ζ

-0.019712ζ

.sup.2)T.sub.d

space="preserve" listing-type="equation">t.sub.4 =(0.50210+0.15873ζ

-0.22743ζ

.sup.2)T.sub.d

space="preserve" listing-type="equation">t.sub.5 =(0.57439+0.04813ζ

-0.17499ζ

.sup.2)T.sub.d

where ##EQU61##

37. The method of claim 31 wherein V=0.10, P=3 and the approximate solution is:

space="preserve" listing-type="equation">t.sub.1 =0

space="preserve" listing-type="equation">t.sub.2 =(0.10412+0.12667ζ

+0.02201ζ

.sup.2)T.sub.d

space="preserve" listing-type="equation">t.sub.3 =(0.24916+0.11908ζ

-0.06480ζ

.sup.2)T.sub.d

space="preserve" listing-type="equation">t.sub.4 =(0.44925+0.11835ζ

-0.21300ζ

.sup.2)T.sub.d

space="preserve" listing-type="equation">t.sub.5 =(0.52261+0.02720ζ

-0.18377ζ

.sup.2)T.sub.d

where ##EQU62##

38. The method of claim 29 wherein establishing the second constraint comprises constraining the unwanted dynamics at frequencies different from the natural frequency ω

.

39. The method of claim 29 further comprising using a low-pass filter to control unwanted dynamics at frequencies different from the natural frequency ω

.

40. The method of claim 19 wherein establishing the first constraint comprises selecting a peak partial sum for the inputs and the partial sums of the inputs are constrained to stay at or below this peak partial sum.

41. The method of claim 40 wherein the peak partial sum of the inputs is chosen based on the peak physical input to the physical system.

42. The method of claim 19 wherein establishing the first constraint comprises selecting a peak duty cycle for the inputs and the duty cycles of the inputs are constrained to stay at or below this peak duty cycle.

43. The method of claim 42 wherein the peak duty cycle for the inputs is chosen based on the peak duty cycle of the physical input to the physical system.

44. The method of claim 19 wherein the dynamic system has p vibrational modes characterized by undamped natural frequencies ω

_i and damping ratios ζ

_i, i=1 . . . p, establishing p sets of constraint equations with the equations representing the first and second series of constraints, and finding a minimum length solution while still satisfying the p sets of constraints.

45. The method of claim 19 wherein the solution is a sequence of an odd number, n, of impulses, which amplitude are given by

46. The method of claim 19 wherein the solution is a sequence of an even number of impulses, which amplitude are given by

47. The method of claim 45 wherein the dynamic system is modelled as M masses, m.sub.,m₂, . . . m_M, connected by springs, and has p vibrational modes each characterized by an undamped natural frequency ω

_i and damping ratio ζ

_i, i=1 . . . p; and

the locations of the impulses are defined by the equation ##EQU63## where Σ

m is the sum of the M masses and x_d is a pre-selected distance to be moved, and the equations ##EQU64## for each of the p modes, where ω and

ζ

are the undamped natural frequency and damping constant for the mode, t_i is the location of the ith impulse, t₁ has been arbitrarily set to 0, V is the bound on the residual vibrations of the physical system, and ω

_hi and ω

_low are a frequency above and below the natural frequency ω

for which the residual vibration is reduced to zero.

48. The method of claim 47 wherein M=2, p=1, and n=7.

49. The method of claim 19 further comprising:

establishing third constraints bounding variations in physical system characteristics;

finding a minimum length solution which is used to generate the input while satisfying the first, second and third constraints; and

controlling the physical system based on the input to the physical system whereby unwanted dynamics are minimized.

50. The method of claim 49 wherein the solution is a minimum length sequence of impulses which satisfies the first, second and third constraints;

and finding the minimum length solution comprises first determining the number of impulses required, and then determining the amplitudes and locations of each impulse.

51. The method of claim 50 wherein determining the number of impulses required comprises the use of a decision tree.

52. The method of claim 51 wherein the dynamic system is characterized by an undamped natural frequency ω

and damping ratio ζ

;

the second constraint comprises selecting a bound, V=0.05, on the residual vibrations of the physical system;

the third constraint comprises selecting an insensitivity, I, bounding the variation of ω

; and

the number of impulses is determined by using the following decision tree;

space="preserve" listing-type="equation">if I<

0.06363+0.01044ζ

+0.07064ζ

.sup.2 +0.40815ζ

.sup.3,

then the number of impulses=2;

space="preserve" listing-type="equation">if I<

0.3991+0.6313ζ

+0.3559ζ

.sup.2 +2.3052ζ

.sup.3

space="preserve" listing-type="equation">and I>

0.06363+0.01044ζ

+0.07064ζ

.sup.2 +0.40815ζ

.sup.3,

then the number of impulses=3;

space="preserve" listing-type="equation">if I>

0.3991+0.6313ζ

+0.3559ζ

.sup.2 +2.3052ζ

.sup.3

then the number of impulses=4.

53. The method of claim 49 wherein the dynamic system has a single vibrational mode characterized by an undamped natural frequency ω

and damping ratio ζ

;

the second constraint comprises bounding the residual vibrations in the physical system; and

the third constraint comprises bounding the variation on ω

.

54. The method of claim 49 wherein the dynamic system has a single vibrational mode characterized by an undamped natural frequency ω

and damping ratio ζ

;

the second constraint comprises bounding the residual vibrations in the physical system; and

the third constraint comprises bounding the variation on ζ

.

55. A method for controlling a physical system by generating an input to the system to minimize unwanted dynamics in the system response comprising;

establishing expressions quantifying the unwanted dynamics;

establishing first constraints bounding an available input to the dynamic system;

establishing second constraints on variation in system response with variations in the physical system characteristics;

finding a minimum length solution which is used to generate the input while satisfying the first and second constraints; and

controlling the physical system based on the input to the physical system whereby unwanted dynamics are minimized.

56. The method of claim 55 wherein the solution is a minimum length sequence of impulses which satisfies the first and second constraints.

57. The method of claim 55 wherein the solution is a minimum length sequence of pulses of finite duration which satisfies the first and second constraints.

58. The method of claim 55 wherein the solution is a sequence of impulses or pulses that begin at specified time intervals.

59. The method of claim 55 wherein the solution is a sequence of impulses or pulses which have specified amplitudes.

60. The method of claim 55 wherein the solution is a sequence of pulses which are fixed in amplitude but variable in duration.

61. The method of claim 55 wherein the solution is a sequence of impulses or pulses which are viable in amplitude but fixed in duration.

62. The method of claim 55 wherein the physical system is an electrical system.

63. The method of claim 55 wherein the physical system is a mechanical system.

64. The method of claim 55 wherein the physical system is an chemical system.

65. The method of claim 55 wherein the dynamic system has a single vibrational mode characterized by an undamped natural frequency ω

and damping ratio ζ

; and

the solution is a sequence of impulses or pulses of finite duration.

66. The method of claim 65 wherein the sequence contains an odd number, n, of impulses with amplitudes given by the following equations:

space="preserve" listing-type="equation">A.sub.1 =P

space="preserve" listing-type="equation">A.sub.i =2P(-1).sup.i-1 for 1<

i<

n

space="preserve" listing-type="equation">A.sub.n =P+1

where P is a pre-selected peak partial sum for the inputs.

67. The method of claim 66 wherein n=3, the damping ratio ζ

=0 and the locations of the three impulses are defined by the equations

space="preserve" listing-type="equation">t.sub.1 =0 ##EQU65## where T=2π

/ω

.

68. The method of claim 66 wherein n=3, P=1, and the locations of the three impulses are approximated by the following equations

69. The method of claim 66 wherein n=3, P=2, and the locations of the three impulses are approximated by the following equations

70. The method of claim 66 wherein n=3, P=3, and the locations of the three impulses are approximated by the following equations

71. The method of claim 66 wherein n=3, and the location of the third impulse is approximated by the equation ##EQU69##

72. The method of claim 66 wherein n=5, P=1, and the locations of the five impulses are approximated by the following equations:

space="preserve" listing-type="equation">t.sub.1 =0

space="preserve" listing-type="equation">t.sub.2 =(0.15236+0.23230ζ

+0.09745ζ

.sup.2)T.sub.d

space="preserve" listing-type="equation">t.sub.3 =(0.27750+0.10237ζ

-0.00612ζ

.sup.2)T.sub.d

space="preserve" listing-type="equation">t.sub.4 =(0.63139+0.33716ζ

-0.07724ζ

.sup.2)T.sub.d

space="preserve" listing-type="equation">t.sub.5 =(0.67903+0.18179ζ

-0.06008ζ

.sup.2)T.sub.d

where ##EQU70##

73. The method of claim 66 wherein n=5, P=2, and the locations of the five impulses are approximated by the following equations:

space="preserve" listing-type="equation">t.sub.1 =0

space="preserve" listing-type="equation">t.sub.2 =(0.11700+0.15424ζ

+0.03449ζ

.sup.2)T.sub.d

space="preserve" listing-type="equation">t.sub.3 =(0.26041+0.11899ζ

-0.05910ζ

.sup.2)T.sub.d

space="preserve" listing-type="equation">t.sub.4 =(0.49378+0.15092ζ

-0.25380ζ

.sup.2)T.sub.d

space="preserve" listing-type="equation">t.sub.5 =(0.56273+0.04255ζ

-0.19898ζ

.sup.2)T.sub.d

where ##EQU71##

74. The method of claim 66 wherein n=5, P=3, and the locations of the five impulses are approximated by the following equations:

space="preserve" listing-type="equation">t.sub.1 =0

space="preserve" listing-type="equation">t.sub.2 =(0.10022+0.11695ζ

+0.00246ζ

.sup.2)T.sub.d

space="preserve" listing-type="equation">t.sub.3 =(0.24352+0.10877ζ

-0.08790ζ

.sup.2)T.sub.d

space="preserve" listing-type="equation">t.sub.4 =(0.44109+0.11059ζ

-0.23127ζ

.sup.2)T.sub.d

space="preserve" listing-type="equation">t.sub.5 =(0.51155+0.02121ζ

-0.20054ζ

.sup.2)T.sub.d

where ##EQU72##

75. A method for controlling a physical system by generating an input to a dynamic system with p vibrational modes characterized by undamped natural frequencies ω

and damping ratios ζ

_i, i=1 . . . p, to minimize unwanted dynamics in the physical system response comprising;

defining a sequence of n=2p+1 impulses by the equations ##EQU73## for each of the p vibrational modes, ##EQU74##

space="preserve" listing-type="equation">t.sub.1 =0

space="preserve" listing-type="equation">A.sub.i ≧

0

where A_i are the amplitudes of the impulses and t_i are the locations of the impulses;

approximating the solution to the defining equations; and

controlling the physical system based on the generated input to the physical system whereby unwanted dynamics are minimized.

76. The method of claim 75 wherein p=2 and the solutions to the equation are approximated by the following equations

77. A method for controlling a physical system by generating an input to the system to minimize unwanted dynamics in the system response comprising;

establishing first constraints on a sequence of impulses which minimize the unwanted dynamics;

determining a first sequence of impulses which satisfies the first constraints;

determining a second sequence of impulses, which is discretized in locations and is used to generate the input, by determining the number of impulses and the locations of the impulses of the second sequence based on the first sequence;

determining the amplitudes of the second sequence to satisfy second constraints based on the first constraints; and

controlling the physical system based on the input to the physical system whereby unwanted dynamics are minimized.

78. The method of claim 77 wherein the first sequence is a sequence of n impulses and the second sequence is a sequences of 2n-1 impulses.

79. The method of claim 78 wherein

the dynamic system has a single vibrational mode characterized by an undamped natural frequency ω

and non-zero damping ratio ζ

;

the constraints are given by the equations ##EQU76## where A_i and t_i are the amplitudes and locations of the impulses;

the first sequence is a three-impulse sequence which satisfies the constraints; and

the second sequence is a five-impulse sequence which satisfies the constraints, the locations of the impulses being given by

space="preserve" listing-type="equation">t.sub.1 =0.0

space="preserve" listing-type="equation">t.sub.2 =dt*floor(t/dt)

space="preserve" listing-type="equation">t.sub.3 =t.sub.2 +dt

space="preserve" listing-type="equation">t.sub.4 =dt*floor(2*t/dt)

space="preserve" listing-type="equation">t.sub.5 =t.sub.4 +dt

where t is the time between impulses for the three-impulse sequence and dt is the time increment for the discretized times, and the amplitudes being given by

space="preserve" listing-type="equation">A=M.sup.-1 V

where ##EQU77##

80. A method for controlling a physical system by generating an input to a dynamic physical system to reduce the deviation between the shape of a trajectory traversed by a point in the physical system and a pre-selected shape comprising:

establishing constraints on the available inputs to the dynamic system to define a group of possible inputs;

determining an impulse sequence which eliminates unwanted dynamics in the physical system;

convolving the impulse sequence with each input in the group of possible inputs to determine a group of shaped inputs;

determining the shaped input which minimizes the deviation between the shape of the actual trajectory and the pre-selected shape; and

controlling the physical system based on the shaped input which minimizes the deviation between the shape of the actual trajectory and the pre-selected shape, whereby the deviation is minimized.

81. The method of claim 80 wherein the pre-selected shape is a circle or part of an arc.

82. The method of claim 81 wherein the group of possible inputs comprises inputs which produce circular trajectories with diameters greater than that of the pre-selected shape.

83. The method of claim 80 wherein the pre-selected shape is a polygon.

84. The method of claim 83 wherein the polygon is a rectangle.

85. The method of claim 83 wherein the group of possible inputs comprises inputs which result in delays at one or more vertices of the polygonal trajectory.

86. The method of claim 80 wherein the physical system comprises two or more different modes and the unwanted dynamics of the physical system are minimized by minimizing the unwanted dynamics of each mode individually.

87. The method of claim 80 wherein the physical system comprises two or more different modes and the unwanted dynamics of the physical system are minimized by minimizing the unwanted dynamics of all modes simultaneously.

88. The method of claim 80 wherein the physical system performs an operation while traversing the trajectory of pre-selected shape.

89. The method of claim 88 wherein a beginning of the operation is delayed with respect to a beginning of the trajectory.

90. The method of claim 88 wherein the operation is a machining operation.

91. The method of claim 88 wherein the operation is a welding operation.

92. The method of claim 88 wherein the operation is a measuring operation.

93. The method of claim 80 further comprising initiating the trajectory in a direction parallel to a direction of a lowest natural frequency of the physical system.

94. The method of claim 80 wherein the group of possible inputs comprises inputs which produce trajectories of a pre-selected shape but differing initial directions.

95. A method for controlling a physical system by generating an input to a dynamic system to minimize unwanted dynamics in the physical system response comprising:

establishing expressions quantifying the unwanted dynamics;

establishing first constraints on the available inputs to the dynamic system to define a group of possible inputs;

expressing each input in the group of possible inputs as a combination of one or more primitive input trains;

determining the combination which minimizes the unwanted dynamics;

controlling the physical system based on the input in the group of possible inputs which corresponds to the combination which minimizes the unwanted dynamics, whereby unwanted dynamics are minimized.

96. The method of claim 95 wherein the primitive input trains are sequences of impulses or sequences of finite duration pulses.

97. The method of claim 95 wherein the first constraint comprises limiting the group of possible inputs to inputs which generate trapezoidal velocity profiles.

98. The method of claim 97 wherein the physical system is characterized by a vibrational frequency, f;

each trapezoidal velocity profile is characterized by a time required to reach maximum velocity, t₁, and a time at which deceleration begins, t₂ ;

the primitive input trains are sequences of impulses; and

determining the combination which minimizes the unwanted dynamic comprises determining the distance from m₁ =t₁ *f or m₂ =t₂ *f to the closest integer.

99. The method of claim 98 wherein determining the combination which minimizes the unwanted dynamic further comprises requiring either m₁ or m₂ to be an integer or approximately an integer.

100. The method of claim 98 wherein determining the combination which minimizes the unwanted dynamic further comprises requiring both m₁ and m₂ to be an integer or approximately an integer.

101. The method of claim 95 wherein the first constraint comprises limiting the group of possible inputs to inputs which generate s-curve velocity profiles.

102. The method of claim 101 wherein the physical system is characterized by a vibrational frequency, f;

each s-curve velocity profile is characterized by a time required to reach maximum acceleration, t₀, a time at which constant acceleration ends, t₁, and a time at which deceleration begins, t₂ ;

the primitive input trains are sequence of impulses; and

determining the combination which minimizes the unwanted dynamic comprises determining the distance from m₀ =t₀ *f, m₁ =t₁ *f or m₂ =t₂ *f to the closest integer.

103. The method of claim 102 wherein determining the combination which minimizes the unwanted dynamic further comprises requiring either m₀, m₁ or m₂ to be an integer or approximately an integer.

104. The method of claim 102 wherein determining the combination which minimizes the unwanted dynamic further comprises requiring two of the three values m₀, m₁ and m₂ to be an integer or approximately an integer.

105. The method of claim 102 wherein determining the combination which minimizes the unwanted dynamic further comprises requiring m₀, m₁ and m₂ to be an integer or approximately an integer.

106. The method of claim 95 wherein the first constraint comprises limiting the group of possible inputs to inputs which generate parabolic velocity profiles.

107. The method of claim 106 wherein the physical system is characterized by a vibrational frequency, f;

each parabolic velocity profile is characterized by a distance moved x_f, a velocity v_max, all acceleration a_max and a jerk jerk;

the primitive input trains are sequence of impulses; and

determining the combination which minimizes the unwanted dynamic comprises determining the distance from m₁ or m₂ to the closest integer, and determining the distance from n₁ or n₂ to the closest integer, where

space="preserve" listing-type="equation">m.sub.1 =[x.sub.f /v.sub.m +a.sub.max /(2jerk)]f

space="preserve" listing-type="equation">m.sub.2 =[v.sub.max /a.sub.max -a.sub.max /(2jerk)]f

space="preserve" listing-type="equation">n.sub.1 =[x.sub.f /v.sub.max -v.sub.max /a.sub.max ]f-0.5

space="preserve" listing-type="equation">n.sub.2 =[a.sub.max /jerk]f.

108. The method of claim 107 wherein determining the combination which minimizes the unwanted dynamic further comprises requiring either m₁ or m₂, and either n₁ or n₂ to be an integer or approximately an integer.

109. The method of claim 107 wherein determining the combination which minimizes the unwanted dynamic further comprises requiring m₁, m₂, n₁ and n₂ to be an integer or approximately an integer.

110. A method for shaping an arbitrary command input to a dynamic physical system to reduce unwanted dynamics in the physical system comprising:

determining a first parameterization for the arbitrary command input;

determining an impulse sequence which eliminates unwanted dynamics in the physical system;

determining a second parameterization to express the convolution of the impulse sequence with the arbitrary command input; and

controlling the input to the physical system based on the second parameterization, whereby unwanted dynamics in the physical system are minimized.

111. The method of claim 110 wherein the first parameterization is piece-wise flat.

112. The method of claim 110 wherein the first parameterization is piece-wise linear.

113. The method of claim 110 wherein the second parameterization is piece-wise linear.

114. The method of claim 110 wherein the second parameterization is piece-wise polynomial.

115. The method of claim 110 wherein the controlling of the input to physical system comprises the use of a lookup table.

116. An apparatus for controlling a physical system by reducing the deviation between the shape of a trajectory traversed by a point in a dynamic physical system and a pre-selected shape comprising:

computing apparatus for determining an impulse sequence which eliminates unwanted dynamics in the physical system;

apparatus for selecting an input from a group of possible inputs which, when convolved with the impulse sequence, minimizes the deviation between the shape of the actual trajectory and the pre-selected shape; and

apparatus for controlling the physical system based on the convolution of the impulse sequence with the selected input whereby the deviation between the shape of the actual trajectory and the pre-selected shape is minimized.

117. An apparatus for controlling a physical system by shaping an arbitrary command input to a physical system in order to minimize unwanted dynamics in a physical system response comprising:

a sensor for measuring the unwanted dynamics;

computing apparatus for determining natural frequencies of the unwanted dynamics based on the measurement of the unwanted dynamics;

apparatus for determining a sequence of impulses, a sequence of pulses, or a trajectory which minimizes the unwanted dynamics at the natural frequencies;

apparatus for convolving the sequence of impulses with the arbitrary command input to produce a shaped command input; and

apparatus for controlling the physical system based on the shaped command input whereby the unwanted dynamics are minimized.

118. An apparatus for minimizing unwanted dynamics in a physical system response comprising:

computing apparatus for expressing each input in a group of possible inputs as a combination of impulse sequences and a step function;

apparatus for determining which of the combinations of impulse sequences minimizes the unwanted dynamics;

apparatus for controlling the physical system based on the input which corresponds to the combination of impulse sequences which minimizes unwanted dynamics.

119. Apparatus for controlling a physical system by shaping an input to a dynamic physical system to reduce unwanted dynamics in the physical system comprising:

apparatus for determining a command which eliminates unwanted dynamics in the physical system;

computing apparatus for splitting the command into an impulse sequence and an input such that the command is obtained if the input and the impulse sequence are convolved together;

apparatus for convolving the sequence of impulses with an arbitrary command input to produce a shaped output; and

apparatus for controlling the physical system based on the shaped input whereby unwanted dynamics are minimized.

120. An apparatus for reducing unwanted dynamics in a physical system response of a closed loop dynamic system comprising:

a first filter which is based on an impulse sequence which eliminates unwanted dynamics in the physical system response and which is located in a feed-forward branch of the closed loop system; and

a second filter which is based on an inverse of the first filter and which is located in the feed-back branch of the closed loop system, whereby unwanted dynamics are minimized.

121. The apparatus of claim 120 wherein the filters are analog filters.

122. The apparatus of claim 120 wherein the filters are digital filters.

123. The apparatus of claim 120 wherein the second filter is variable.

124. The apparatus of claim 123 wherein varying the second filter is mathematically equivalent to varying the closed loop system from a system with no second filter and the first filter in the feed-forward branch of the closed loop to a system with no second filter and the first filter outside the closed loop.

125. A method for reducing unwanted dynamics in a physical system response of a closed loop dynamic system comprising:

determining an impulse sequence which eliminates unwanted dynamics in the physical system response;

inserting a first filter based on the impulse sequence in a feed-forward branch of the closed loop system; and

inserting a second filter based on an inverse of the first filter in the feed-back branch of the closed loop system whereby unwanted dynamics are minimized.

126. A method for controlling a physical system by generating an input to a dynamic system to minimize unwanted dynamics in a physical system response comprising:

establishing expressions quantifying the unwanted dynamics;

establishing first constraints bounding an available input to the dynamic system;

establishing desired values for the unwanted dynamics at pre-selected values of a physical system characteristic;

establishing an error measure based on the differences between the desired values for the unwanted dynamics and the expressions quantifying the unwanted dynamics when evaluated at the pre-selected values of the physical system characteristic;

finding a solution which minimizes the error measure and is used to generate the input while still satisfying the first constraints; and

controlling the physical system based on the input to the physical system whereby unwanted dynamics are minimized.

127. The method of claim 126 wherein the solution is a sequence of impulses.

128. The method of claim 126 wherein the solution is a sequence of pulses of finite duration.

129. The method of claim 126 wherein the solution is a sequence of impulses or pulses which begin at specified time intervals.

130. The method of claim 126 wherein

the dynamic system is characterized by an undamped natural frequency ω

and damping ratio ζ

,

the solution is a sequence of n impulses of amplitude A_i and location t_i, for i=1 . . . n, with t₁ =0;

the expression quantifying the unwanted dynamics is

space="preserve" listing-type="equation">R(Ω

)= exp (-ζ

Ω

t.sub.N){[Σ

A.sub.i exp (ζ

Ω

t.sub.i) cos (mΩ

t.sub.i)].sup.2 +[Σ

A.sub.i exp (ζ

Ω

t.sub.i) sin (mΩ

t.sub.i)].sup.2 }.sup.1/2

where m=(1-ζ

²)^1/2, R(Ω

) is the ratio of the residual vibration produced by the sequence of impulses to the residual vibration produced by a single impulse of amplitude Σ

A_i, if the physical system had an undamped natural frequency Ω

, and the summation is over i=1 . . . n,

the pre-selected values of the physical system characteristic are the undamped natural frequencies ω

_j, j=1 . . . N,

the desired values for the unwanted dynamics are D_j, j=1 . . . N,

the error measure is

space="preserve" listing-type="equation">E=Σ

[D.sub.j -R(ω

.sub.j)].sup.2

where the summation is over j=1 . . . N, and

finding a solution is accomplished using a method of least squares.